1. Field of the Invention
The present invention relates to a solenoid-operated switch for a starter for an automobile to control a current to be fed to the starter.
2. Discussion of Background
FIG. 2 shows a conventional solenoid-operated switch for a starter of this kind. In FIG. 2, a movable contact 1 is attached to a rod 3 through an insulator 2. The rod 3 is inserted in a core 4 so as to be slidable in its axial direction. A stationary contact 5 is fixed to a cap 6 of an insulating material, which is a rear part of the solenoid-operated switch, by means of a nut so as to face the movable contact 1. An annular exciting coil 8, which is wound on a bobbin made of a resinous material, is attached to the inner wall of an iron housing 11. A plunger 9 is inserted in the exciting coil 8 to be movable in its axial direction upon exciting the coil 8. A socket portion 11a is formed at the rear part of the housing 11. The outer periphery of the core 4 and the front end part of the cap 6 are fixed to the socket portion 11a by a caulking operation. A reference numeral 12 designates a lead wire for connecting the stationary contact 5 to brushes (not shown) in the starter.
The conventional solenoid-operated switch operates as follows.
On turning a key switch (not shown), the exciting coil 8 is actuated to move the plunger 9 backwardly (on the lefthand in FIG. 2). Then, the rod 3 is pushed backwardly to bring the movable contact 1 in contact with the stationary contact 5, whereby an electric current is fed to the brushes of the starter through the lead wire 12 via the stationary contact so that an armature produces a torque.
In the conventional solenoid-operated switch having the stationary and movable contacts which are mutually brought to contact in the cap 6, when they come to contact with each other, there takes place sparks which cause noises or electromagnetic induction. The noises easily leak outside and may result in erroneous ignition to the engine through a cord of the distributor, for instance.